Smoke from under engine cover

[k_krobbins]

I have a 2004 50hp 2 stroke Merc O/B, someone disconnected the warning buzzer, so i reconnected it and the buzzer buzzes constantly (bad temp sender ?). Also noticed while i had cover off and running that while throttling up engine it wants to hesitate and almost sounds like an exhaust leak then a puff of blue smoke comes from the engine (almost like a backfire). So when i give it gas is when it does this.

 

[k_krobbins]

Re: Smoke from under engine cover

Any suggestions? Also i need a repair manual and can't find one locally, are the on-line manuals just as good?